1. Field of the Invention
The present invention relates to an applicator and method of applying fluid sealant agents to a work surface and is particularly, although not exclusively, useful for applying two-component tissue sealant agents to biological tissue to effect hemostasis or achieve other therapeutic results. More particularly, it relates to a hand-held applicator and methods of application of tissue sealants from a hand-held applicator.
2. Description of Related Art Including Information Disclosed under 37 CFR 1.97 and 37 CFR 1.98
Application of tissue sealants and other biologically derived or biologically functional materials to close wounds, control bleeding, control fluid leakage or oozing or to fulfill other therapeutic or preparative purposes, is an important emerging surgical technique, well adapted for the operating room or field environments such as the doctor's office or mobile medical units. Preferred sealants include fibrin sealants which are formed from blood plasma components and comprise, on the one hand, a first agent containing fibrinogen and Factor XIII, and on the other hand a second agent which usually includes thrombin, and calcium ions. The fibrinogen is capable of a polymerizing and being cross-linked to form a solid fibrin clot when the agents are mixed. The necessary additional factors to simulate relevant portions of the natural blood coagulation cascade are suitably distributed between the fibrinogen and thrombin agents.
High levels of protection against transmission of infections or induction of immunological reactions can be assured by using an autologous or single-donor source for both agents. Such sealants are highly effective, are biologically degraded without residue and may promote wound healing. Other biologically derived or biologically functional agents may be applied together with or in lieu of the tissue sealant.
Depending upon the potency of the particular formulations employed, polymerization or coagulation of the sealant may take place very rapidly, yielding a gel within perhaps 10 or 20 seconds. Though often desirable for surgical reasons, such fast-acting properties present potential problems of fouling or clogging. These problems must be overcome in devising suitable applicators, and methods of application.
Antanavich et al. U.S. Pat. No. 5,585,007, whose disclosure and references are hereby incorporated herein by reference thereto, provides an extensive discussion of the literature relating to fibrinogen sealant preparation (column 1, line 20 to column 4, line 62) and applicators column 4 line 62 to column 5, line 14), as well as a bibliography, (columns 6-10) and is a helpful guide to the teachings of prior workers in the field.
A popular manually operable applicator for such two-agent sealants employs a dual syringe construction having two syringes each of which provides a reservoir for one of the agents. Plungers, connected together by a yoke, are advanced within the syringes, to dispel the agents from the applicator. In many prior devices the sealant agents are discharged in separate streams and mixed externally of the applicator. Such applicators are similar in principle to household epoxy glue applicators commonly available in hardware stores, see for example Creighton et al. U.S. Pat. No. 3,828,980. Achieving effective mixing externally of the applicator is problematic and the resultant sealant product is often inadequately mixed and performs unsatisfactorily. Poor mixing may result in any one or more of the drawbacks of Slow polymerization, poor adhesion and cohesion, low bond strength, uneven distribution of the sealant on the work surface, inadequate coverage and poor film or spray formation.
It would be desirable to have a manually operable tissue sealant applicator which mixed two or more agents prior to discharge from the applicator, and in U.S. Pat. No. 5, 266,877, and the above applications, Gordon H. Epstein, and others, teach various constructions of a dual syringe applicator which provide internal mixing. A problem that arises is that such an applicator must necessarily have a mixed agent pathway within the device, extending from a point of mixing of the agents to a point of discharge from the device, and this mixed agent pathway is prone to clogging, obstruction or contamination with gelled or solidified sealant.
In the related applications, the possibility of retrograde clearing of the mixed fluids pathway within the applicator, using suction, is also disclosed. Thus, the related applications teach a method of applying a tissue sealant or the like, which comprises mixing two or more sealant agents in an applicator, dispelling the mixed agents from the applicator along a mixed agent pathway and clearing the mixed agent pathway of undesired residues. In a preferred embodiment (of the related applications) the applicator is provided with suitable suction conduits and valving to apply suction to the work surface for various purposes, for example to prepare the work surface for the application of sealant, for example by removing fluids, or to grip and manipulate tissue. As taught, the valving is operable to effect retrograde clearing of a sealant dispensing pathway. Enhanced mixing results and problems of fouling by deposited solids are avoided. Drawbacks are that such applicators require a suitable suction source, which may not always be available, and the magnitude of the clearing force that can be applied by suction is limited.
Related application Ser. No. 09/037,160, also discloses an alternative embodiment of the above-described clearing method which comprises disposing of the clogged structures between sealant applications by removing a disposable agent from the applicator. For this purpose the applicator is provided with a disposable sealant dispensing cannula which may extend into a mixing chamber where the sealant agents are mixed. However, component disposability entails costs and inconveniences and may result in loss of valuable sealant of limited availability. Fast acting fibrinogen sealants that clot rapidly may require the cannula to be changed after every use, which may not be practical during a complex surgical procedure,
It would therefore be desirable to have a sealant applicator and application method providing internal mixing which solves the prior art clogging problems without requiring a suction source or disposable components.